Originally Posted by
Semaphore
If you had fully researched the lab/temple/church skills, then sure, spend your souls on soul tickets. And once you get up into the tens of thousands of souls, it's okay to use some on soul tickets. But if you can't keep the lab and temple/church on cooldown because you're out of souls, you're doing it wrong.
Just leveling a single skill from 50 to 65 takes 9000 souls, 108 million copper, and more than 2 months worth of cooldowns. Multiply by 25 skills and we're talking about 225000 souls, 2.7 billion copper, and several years. And that's just to go from 50 to 65, though that's admittedly far more expensive than going from 0 to 50. So no, you haven't fully leveled that.
At the moment, I have exactly 31162 souls on hand. That means that whenever I need souls for something, such as lab/temple skills or converting EVO card catalogs to Universal EVO cards, I've got them sitting around.